1. Field of the Invention
The present invention relates to a method for manufacturing a circuit board. More particularly, the present invention relates to a method for manufacturing a circuit board having built-in electronic components, capable of ensuring high reliability.
2. Background of the Related Art
A circuit board is a part for electronic apparatuses and serves as a base plate for mounting electronic components thereon. Further, the circuit board electrically connects electronic components mounted thereon to each other, and holds the electronic components. Recently, circuit boards are becoming more important parts because electronic apparatuses using the circuit boards are becoming more complex. In order to respond to this trend, that is, in order to increase the degree of integration of electronic components in a circuit board, a multi-layered circuit board, in which a plurality of circuit boards are stacked, and an integrated circuit board, in which electronic components are built in, have been developed.
Currently, a plurality of methods of mounting electronic components on a circuit board is disclosed, and one example thereof is disclosed in Japanese Patent Laid-Open Publication number 2002-246757, entitled “Method of Manufacturing Multi-layered Printed Circuit Board.” For reference, the example is described hereinafter with reference to FIGS. 6A to 6E.
First, referring to FIG. 6A, a core substrate 30 having a through hole 32 is prepared. The lower part 32a of the through hole 32 is tapered. That is, the tapered portion of the through hole 32 becomes larger toward its lower end.
Next, referring to FIG. 6B, ultraviolet tape (UV-tape) 40 is attached to the lower surface of the core substrate 30 to close the lower end of the through hole 32.
Next, referring to FIG. 6C, a chip 20 is installed in the through hole 32 on the UV-tape 40 in a manner such that die pads 38 of the chip 20 are adhered onto the upper surface of the UV tape 40.
Next, referring to FIG. 6D, the hole 32 is filled with a filler 41, and air in the filler 41 is removed by decompressing the hole 32.
Finally, referring to FIG. 6E, the core substrate 30 is pressurized and/or heated in the vertical direction by stainless press plates 100A and 100B.
The conventional method has disadvantages in that the chip 20 is difficult to mount on a desired position on the UV-tape 40 because the chip 20 is fixed in the core substrate 30 in a manner such that the chip 20 is weakly adhered on the UV-tape 40 and is then securely fixed when the filter 40 is cured using the press. That is, even if the chip 20 is mounted on the desired position when attaching the chip 20 on the UV-tape 40, the chip 20 can be moved or detached from the UV-tape 40, thereby being displaced from its desired mounting position when the hole 32 is filled with the filler 41. Accordingly, the reliability of the circuit board cannot be guaranteed.